[llvm-bugs] [Bug 26266] New: wrong code at -O1 and above in 32-bit and 64-bit modes on x86_64-linux-gnu

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=26266

            Bug ID: 26266
           Summary: wrong code at -O1 and above in 32-bit and 64-bit modes
                    on x86_64-linux-gnu
           Product: clang
           Version: trunk
          Hardware: PC
                OS: Windows NT
            Status: NEW
          Severity: normal
          Priority: P
         Component: -New Bugs
          Assignee: unassignedclangbugs at nondot.org
          Reporter: chengniansun at gmail.com
                CC: llvm-bugs at lists.llvm.org
    Classification: Unclassified

The following code is miscompiled by the trunk at -O1 and above in both 32-bit
and 64-bit modes on x86_64-linux-gnu. 


$: clang-trunk -v
clang version 3.9.0 (trunk 258508)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/bin
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.9
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.9.3
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/5.2.1
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7.3
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9.3
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.2.1
Found candidate GCC installation:
/usr/local/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.6.3
Found candidate GCC installation:
/usr/local/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.7.4
Found candidate GCC installation:
/usr/local/bin/../lib/gcc/x86_64-unknown-linux-gnu/4.8.2
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64
$: 
$: clang-trunk -w -O0 small.c ; ./a.out
$: clang-trunk small.c -O1 -m32 ; ./a.out
Aborted (core dumped)
$: clang-trunk small.c -O1 -m64 ; ./a.out
Aborted (core dumped)
$: 
$: cat small.c
void abort();
char a;
int b, c = 9, d, e;
void fn1() {
  unsigned f = 1;
  int g = 8, h = 5;
  for (; a != 6; a--) {
    int *i = &h, *j;
    for (;;) {
      int k = e, l = ~1;
      if (g && h) {
        k = g;
        l = f;
        f = -(~(c && b) | -~(e * ~l));
        if (c < f)
          abort();
      }
      g = k;
      f = l;
      if (d <= 8)
        break;
      *i = 0;
      for (; *j <= 0;)
        ;
    }
  }
}
int main() {
  fn1();
  return 0;
}
$:

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